As drilling for oil and gas reserves has become more complicated and expensive, the need for high resolution images and diagnostic information about the well bore itself has greatly increased. Many downhole tools are currently used to classify properties of the rock, production characteristics of a well, and the completed infrastructure in place on a well bore, but the information is greatly susceptible to different interpretations. For example, different geologists can look at the same well log and derive three completely different interpretations of how the well should be produced and what the characteristics of that production will look like. Furthermore, downhole production measurements are only able to estimate what zones are the most productive and what their individual contributions are to the overall production of the well. The resolution of these production logs leaves a lot to be desired. Similarly, the instrumentation used to inspect the in-place production casing and tubing suffer from resolution issues and are unable to measure some of the more critical characteristics, such as coating thickness and joint integrity.
Horizontal drilling coupled with fracking has greatly expanded the potential production from rock formations. Each frack stage has multiple well bore perforations that allow the frack solution to enter into the formation and fracture, or crack open, the rock to release the hydrocarbons. However, it has been discovered that not all of the perforations become active upon initial injection. In fact, typically only a minority percentage of them actually become conduits for the frack solution to enter the formation and break open the rock, thus releasing the hydrocarbon content of only the active perforations. The result is a large amount of the overall well bore remains unused, but the ability to determine what specific perforations are not active is very difficult.
In addition to the production yield limitations associated with modern drilling, there is also significant need for high resolution imaging of the well bore to help troubleshoot issues with producing wells. These issues can include, but are not limited to, such things as scaling build up in the well, casing integrity, paraffin build up, water contamination, completion design, production tubing issues, leaks, and collapsed sections, just to name a few.
There is a need therefore for a method and system capable of generating a high resolution image of a well bore for inspecting and monitoring activity, including the amount and location of fracking and the degradation of the well bore.